Lighting system for a keyboard

Abstract

An illuminated keyboard that may be used for providing inputs to a computer. The keyboard includes a keyboard base pan and a plurality of input keys having keycaps that may be pressed by a user. An electroluminescent lamp, in the form a flat panel, is sandwiched between the keyboard base pan and the keycaps to illuminate the keyboard during use.

What is claimed is:  
     
       1. A keyboard suitable for use in providing inputs to a computer, comprising: 
       a keyboard base pan;  
       a plurality of input keys extending from the keyboard base pan, each input key having a hollow keycap including an upper strike surface; and  
       an illumination panel having openings above which the keycaps extend, said illumination panel disposed between the keycaps and the keyboard base pan to illuminate the plurality of input keys,  
       each said keycap incorporating a symbol defined by a light transmitting portion at said strike surface.  
     
     
       2. The keyboard as recited in claim  1 , wherein the illumination panel comprises an electroluminescent panel. 
     
     
       3. The keyboard as recited in claim  1 , further comprising a power source configured to provide an output signal to the lamp. 
     
     
       4. The keyboard as recited in claim  3 , wherein the output signal is at a voltage in the range from approximately 50-300 volts peak-to-peak. 
     
     
       5. The keyboard as recited in claim  4 , wherein the output signal has a frequency in the range from approximately 50-1000 hertz. 
     
     
       6. The keyboard as recited in claim  1 , wherein each input key includes an actuator to which the keycap of that input key is attached, said actuator passing through one of said openings in the illumination panel. 
     
     
       7. The keyboard as recited in claim  1 , wherein said symbols include alphanumeric symbols. 
     
     
       8. A keyboard suitable for use in providing inputs to a computer, comprising: 
       a keyboard base pan;  
       a plurality of input keys extending from the keyboard base pan;  
       a lamp disposed to illuminate the plurality of input keys;  
       a power supply connected to said lamp for energization thereof; and  
       logic circuitry responsive to activation of a said input key concurrently with ambient light below a threshold level to enable said power supply to energize said lamp.  
     
     
       9. The keyboard as recited in claim  8 , wherein the power signal is provided to the illumination panel at an a.c. voltage in the range from approximately 50-300 volts peak-to-peak. 
     
     
       10. The keyboard as recited in claim  9 , wherein the power signal has a frequency in the range from approximately 50-1000 hertz. 
     
     
       11. The keyboard as recited in claim  8  wherein said logic circuit comprises a logic gate having a first input coupled to receive logic signal representing actuation of a said input key and a second input coupled to receive logic signal output from a photo detector responsive to ambient light level. 
     
     
       12. A keyboard for use in providing inputs to a computer, comprising: 
       a keyboard base pan;  
       a plurality of input keys extending from the keyboard base pan, each input key having  
       an actuator attached to an inverted cup shaped keycap having an upper strike surface; and  
       a lamp panel having openings therein through which said actuators pass, said lamp panel disposed between said keyboard base pan and said keycaps to illuminate the plurality of input keys;  
       each said keycap including at least one light transmitting symbol at said strike surface, said symbol defined by a light transmissive portion at said strike surface.  
     
     
       13. A keyboard for use in providing inputs to a computer, comprising: 
       a keyboard base pan;  
       a plurality of input keys extending from the keyboard base pan, each input key having an actuator attached to an inverted cup shaped keycap including an upper strike surface, and actuator depending from said strike surface; and  
       a lamp panel having openings therein through which said actuators pass, said lamp panel disposed between said keyboard base pan and said keycaps to illuminate the plurality of input keys;  
       each said keycap incorporating a light transmissive portion defining at least one light transmitting symbol at said strike surface; and  
       logic circuitry comprising a logic gate having a first input for connection to receive a logic signal input representing activation of a said input key and a second input connected to receive logic signal input from a photo detector when ambient light is below a threshold value, to enable said power supply to energize said lamp panel in response to activation of a said input key when ambient light is below said threshold value.  
     
     
       14. The keyboard as recited in claim  13 , wherein said logic circuit comprises a logic gate having a first input responsive to a logic signal representing actuation of a said input key and a second input responsive to a logic signal output from a photo detector.